Originally Posted by
Easy Street
Thank you, I'd missed that. And on re-reading the preliminary report, I see that the NTSB described the routes using amsl. So I stand corrected on the route definition. That brings altimetry errors into play for erosion of the "designed" separation margin, which makes the design even more unsafe. But the point remains that PAT25's 78 foot deviation above the route maximum altitude is within the FAA's tolerance for commercial and instrument flying accuracy by helicopter pilots.
Nothing I'm saying in this post is meant to exonerate FAA or deflect responsibility away from it.
That being said, even though the FAA published a certain tolerance, and the helicopter's 78 foot deviation was within that tolerance, I think it is quite likely (if not certain) that on this particular subpart of the overall factual record, the plaintiffs will argue that the Army knew or should have known that despite the deviation being within the tolerance, such a deviation nonetheless was significantly unsafe and therefore negligent on the Army's part. It would be argued that the Army had a legal duty independent of what FAA published to operate its helicopters safely. The acts and omissions of more than one actor in a given situation can be oustide the established duties of care and therefore negligent. (I'm imagining that military aviators may disagree insofar as it may be an article of faith as well as military regulation that the FAA is absolutely the one responsible party for civil controlled airspace, but as a legal point I think plaintiffs will attack it.)